Andesite flows on Lascar
Volcano -- Located
in Chile, the Lascar volcano is the most active stratovolcano
in the central Andes. The most impressive features on the flanks
of the volcano are two massive andesite flows exhibiting thick
flow margins tens of meters high and well-developed lava levees.
The transverse ridges on the central andesite flow are called
ogives. They develop as folds perpendicular to
the direction of flow, which are sometimes ramped upward along
faults generated by brittle deformation of the flow interior.
Courtesy of Peter Francis.